It is known to either dry or freeze vegetables and fruits for use by consumers. Additionally, it is known to use these two processes in combination to produce frozen dried products, also known as dehydro-frozen, or controlled moisture frozen. While these three methods are well suited to preserve fruits or vegetables, all three methods suffer from various problems.
Dried products have limited uses. Many commercial food products require fresh or fresh-like products for use in manufacturing such products. Additionally, dried products are not always readily substituted for fresh products.
Frozen products produced according to traditional methods suffer from a breakdown in the vegetable or fruit cell wall structure and, as such, have a low textural crispness. Crispness generally relates to the amount of water found in the cells of the vegetable or fruit, and translates into plant textural firmness upon mastication. Crispness is also a function of the structural integrity of the cells. A crisp vegetable is typically imbibed with water, has an intact cell wall structure, and, as such, has a firm, crisp texture. Most importantly, crisp vegetables and fruits have a crunchy and firm texture. For example, turgid or crisp celery will be crisp and crunchy; non-turgid or low crispness celery will be limp. When the cell walls break, water exits and crispness decreases. This means that the product will have a poor or mushy texture and will not retain suitable amounts of water. Typically, with slower freezing techniques, upon thawing, water leaches out of a vegetable or fruit product that has been frozen, resulting in a low texture limp product. As such, a product having fresh-like characteristics is not produced. It is desired to have a frozen product that has a textural crispness similar to a fresh product. It is further desired to have a method for freezing a product other than a mechanical freezer, as this has not worked in producing crisp textured vegetables.
It is further known that products can be partially dried and then frozen in an attempt to preserve or improve crispness by optimizing water content before freezing. Such products, when slow frozen, still suffer from having textural crispness that is not close enough to a fresh-like product. Often the cell wall structure in these products has been damaged.
For these reasons, it is desired to have a process or method for producing a frozen fruit or vegetable which has a crispness similar to a fresh product. It is further desired to have a product that has storage characteristics similar to that of a frozen, or partially dehydrated and then frozen (dehydro-frozen) product. For these reasons, it is desired to have a method or process for producing a frozen product that, when thawed, has fresh-like characteristics, but which can be stored for extended periods of time.